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A technology of bensulfuron-methyl and methyl benzylsulfonamide, which is applied in the field of preparation of bensulfuron-methyl, can solve the problems of low production safety, high product cost, and high cost, and achieve high production safety and small amount of three wastes produced , low cost effect
Inactive Publication Date: 2012-10-03
HEFEI JIUYI AGRI DEV
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The production of triphosgene is not yet scaled, and the price is relatively high. There is no stable raw material in China, resulting in high product cost. At the same time, the toxicity of phosgene cannot be completely ruled out.
It is also reported that the reaction of sodium cyanate and sulfonyl chloride is used to obtain methyl o-formate sulfonyl isocyanate, but the yield is not high
[0005] Therefore, there are disadvantages and deficiencies such as unfriendly environment, low production safety, high cost and low yield in the prior art when preparing bensulfuron-methyl
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Embodiment 1
[0017] In a 500 ml four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a constant pressure dropping funnel, add 45.8 grams of methyl o-formate benzylsulfonamide, 31.65 grams of 2-amino-4,6-dimethoxy Base pyrimidine, 200 ml of dry acetone solvent and 3.67 g of dry 4-dimethylaminopyridine, stir to cool down to 5 °C, dropwise add 32.55 g of ethyl chloroformate, slowly warm up to 15 °C, stir for 3.0 h, filter, wash, Dry to obtain 64.5 grams of white powder, the measured content of bensulfuron-methyl is 96.4%, and the calculated yield is 78.6%.
Embodiment 2
[0019] In a 500 ml four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a constant pressure dropping funnel, add 45.8 grams of methyl o-formate benzylsulfonamide, 31.65 grams of 2-amino-4,6-dimethoxy base pyrimidine, 200 ml of dry tetrahydrofuran solvent and 3.67 g of dry 4-dimethylaminopyridine, stirred and cooled to 5 °C, added dropwise 34.72 g of ethyl chloroformate, slowly raised to 20 °C, stirred for 3.0 h, filtered, washed, Dry to obtain 64.78 grams of white powder, the measured content of bensulfuron-methyl is 96.7%, and the calculated yield is 79.0%.
Embodiment 3
[0021] In a 500 ml four-neck flask equipped with a stirrer, a thermometer, a reflux condenser and a constant pressure dropping funnel, add 45.8 grams of methyl o-formate benzylsulfonamide, 31.65 grams of 2-amino-4,6-dimethoxy Base pyrimidine, 200 ml of dry pyridine solvent and 3.67 g of dry pyridine, stir and cool down to 5 °C, dropwise add 32.55 g of ethyl chloroformate, slowly raise the temperature to 25 °C, stir for 3.0 h, filter, wash, and dry to obtain a white powder 65.28 gram, the measured content of bensulfuron-methyl was 97.2%, and its yield was calculated to be 79.61%.
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Abstract
The invention discloses a new method for preparing bensulfuron. The preparation method comprises the following steps of: reacting o-methyl formate benzene benzyl sulfamide and ethyl chloroformate in a dried organic solvent to obtain o-methyl formate benzene benzyl sulfamide ethyl formate; and then adding 2-amino-4, 6-dimethoxy pyrimidine and a few amount of catalyst to obtain the bensulfuron. According to the invention, the ethyl chloroformate is used as the amide agent to control the reaction temperature and the speed of dropping the ethyl chloroformate, so that the ethyl chloroformate is reacted with the o-methyl formate benzene benzyl sulfamide in the dried organic solvent to obtain the o-methyl formate benzene benzyl sulfamide ethyl formate; then the o-methyl formate benzene benzyl sulfamide ethyl formate is further reacted with 2-amino-4, 6-dimethoxy pyrimidine under the action of the catalyst to obtain bensulfuron; and the purity of bensulfuron is greater than or equal to 95%. With the adoption of the ethyl chloroformate as the raw material, the preparation method of bensulfuron provided by the invention has the advantages of high output, high producing safety, low cost, and small producing amount of the three wastes compared with the traditional isocyanate method and sodium cyanate method.
Description
technical field [0001] The invention relates to the technical field of herbicides and pesticides, in particular to a method for preparing bensulfuron-methyl. Background technique [0002] Bensulfuron-methyl is a broad-spectrum, high-efficiency, and low-toxicity herbicide for paddy fields. It inhibits the biosynthesis of valine and isoleucine, which are indispensable for plants, thereby preventing cell division and growth to achieve the purpose of weeding. The chemical name is N-(4,6-dimethoxypyrimidin-2-yl)-N'-(o-methylbenzylsulfonyl)urea, and the molecular formula is C 16 h 18 N 4 o 7 S, the structural formula is as shown in formula (I). [0003] [0004] At present, its synthetic method generally adopts the isocyanate route, and methyl o-formate benzyl sulfonamide and oxalyl chloride react to obtain methyl o-formate sulfonyl isocyanate; or by methyl o-formate benzyl sulfonamide and phosgene or triphosgene (solid phosgene ) reaction to obtain methyl o-formate sulfon...
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